"Death tugs at my ear and says, 'Live, I am coming.'" Were Supreme Court Justice Oliver Wendell Holmes Jr. alive today, he might ascribe that line not to death but to nuclear terrorism.
Ever since Sept. 11, 2001, Americans have had to live with the knowledge that the next time the terrorists strike, it could be not with airplanes capable of killing thousands but atomic bombs capable of killing hundreds of thousands.
The prospect has created a sense of profound vulnerability. It has shaped our view of government policies aimed at combating terrorism (filtered through Jack Bauer). It helped mobilize support for the Iraq war.
Why are we worried? Bomb designs can be found on the Internet. Fissile material may be smuggled out of Russia. Iran, a longtime sponsor of terrorist groups, is trying to acquire nuclear weapons. A layperson may figure it's only a matter of time before the unimaginable comes to pass. Harvard's Graham Allison, in his book "Nuclear Terrorism," concludes, "On the current course, nuclear terrorism is inevitable."
But remember: After Sept. 11, 2001, we all thought more attacks were a certainty. Yet al-Qaida and its ideological kin have proved unable to mount a second strike.
Given their inability to do something simple -- say, shoot up a shopping mall or set off a truck bomb -- it's reasonable to ask whether they have a chance at something much more ambitious. Far from being plausible, argued Ohio State University professor John Mueller in a presentation at the University of Chicago, "the likelihood that a terrorist group will come up with an atomic bomb seems to be vanishingly small."
The events required to make that happen comprise a multitude of Herculean tasks. First, a terrorist group has to get a bomb or fissile material, perhaps from Russia's inventory of decommissioned warheads. If that were easy, one would have already gone missing.
Besides, those devices are probably no longer a danger, since weapons that are not scrupulously maintained (as those have not been) quickly become what one expert calls "radioactive scrap metal." If terrorists were able to steal a Pakistani bomb, they would still have to defeat the arming codes and other safeguards designed to prevent unauthorized use.
As for Iran, no nuclear state has ever given a bomb to an ally -- for reasons even the Iranians can grasp.